Stainless steel grade 254 SMO™ is a very high end austenitic stainless steel. It is designed with a combination of impact toughness resistance to chloride stress corrosion cracking, and pitting and crevice corrosion with strength that is twice that of the stainless steel 300 series.

For certain applications, grade 254 SMO™ has been reported to be a cost-effective substitute for high nickel and titanium alloys. It is known to possess excellent workability as well.

The following sections will discuss in detail about stainless steel grade 254 SMO™.

Chemical Composition

The chemical composition of stainless steel grade 254 SMO™ is outlined in the following table.

Other Designations

Other designations that are equivalent to stainless steel grade 254 SMO™ include the following.

ASTM A813

ASTM A469

ASTM A269

ASTM A240

ASTM A182 (F44)

ASTM A814

ASTM A312

ASTM A249

Fabrication and Heat Treatment

Machinability

Stainless steel grade 254 SMO™ is quite tough to machine due to the extremely high work hardening rate and lack of sulfur content; however using sharp tools, overpowered machine tools, positive feeds, good amount of lubrication, and slow speeds tend to provide good machining results.

Welding

Welding of stainless steel grade 254 SMO™ requires filler material without which it results in poor strength properties. Filler metals such as AWS A5.14 ERNiCrMo-3, and alloy 625 are recommended. Electrodes used in the process, have to match with AWS A5.11 ENiCrMo-12.

Annealing

Annealing of this material should be performed at 1149-1204°C (2100-2200°F), which should be followed by a water quench.

Hot Working

Forging, upsetting and other operations relating to this material can be performed at 982 – 1149°C (1800 – 2100°F). It is recommended that temperatures do not exceed this range as it would result in scaling and reduction in the workability of the material. To re-attain maximum corrosion resistant properties, it is advisable to perform post-process annealing.

Cold Working

Cold working can be carried out using all the traditional methods; however the process would be tough due to its high work hardening rate. The result will provide the material with increased strength and toughness.

Hardening

Stainless steel grade 254 SMO™ does not respond to heat treatment. Hardening is possible only through cold reduction.